Chemical reactor, refrigerating machine and container provided therewith and reagent cartridge therefor

ABSTRACT

A reagent (26) combines exothermically with a cold refrigerating fluid exiting a refrigerating evaporator during a refrigeration cycle, then releases the refrigerating fluid endothermically once it has been heated to a sufficiently high temperature by means of a heating element (17) during a regeneration cycle during which the released refrigerating fluid condenses in a pressurized tank. The reagent is confined inside stainless steel walls (29, 31, 34) which prevent it from swelling. These walls include perforated tubes (34) lining channels (32) in which the mass exchanges take place during the combining and separating reactions. The heating element (17) is fitted in a central cavity (46). An air flow (54), which is interrupted during regeneration, evacuates the heat of the combining reaction by means of fins (56). The invention prevents the block of reagent from distorting and becoming progressively inoperative over repeated cycles.

DESCRIPTION

"Chemical reactor, refrigerating machine and container providedtherewith, and reagent cartridge therefor"

The present invention relates to a chemical reactor for a refrigeratingmachine or similar.

The present invention also relates to a refrigerating machine providedtherewith.

The present invention also relates to a container provided with such arefrigerating machine.

The invention also relates to a reagent cartridge.

The principle of refrigerating machines functioning by chemical reactionis known.

Starting from a reserve of refrigerating fluid in the liquid state underpressure, the fluid passes through a pressure reduction device and thenan evaporator placed in the enclosure to be cooled. On leaving theevaporator, the gas is taken in by the reactor which contains a reagentwhich, at ambient temperature, is chemically eager for this gas. Thereagent combines chemically with the gas whilst producing a certainamount of heat.

When the reserve of liquid under pressure is exhausted, the processstops and it is then necessary to initiate a regeneration processconsisting of supplying heat to the chemical reactor so that the reagentchemically separates from the refrigerating gas and delivers this gasunder high pressure. On leaving the reactor, the gas passes through acondenser and is then collected in the liquid state in the reserve. Whenthe regeneration process is complete, the reserve is at its maximumlevel and a new refrigeration process can be initiated.

This principle which is known at present raises serious implementationproblems.

In service, the reagent is subjected to high stresses, particularlythose of temperature and pressure, and it must furthermore be capable ofabsorbing refrigerating fluid chemically and of separating from itchemically at a speed corresponding to the refrigerating fluid flowrates in the machine.

From U.S. Pat. No. 2,649,700 there is known a chemical reactor for arefrigerating machine or similar comprising several elementary blocks ofreagent intended to absorb, by chemical combination, a gaseous flowcoming from an evaporator and of desorbing this flow by reverse chemicalreaction under the effect of a rise in temperature. The blocks, ofgenerally annular shape, are confined between an internal wall and aperipheral wall. Furthermore, porous screens separate the elementaryblocks from one another. They distribute the gaseous flow between theupper and lower surfaces of the elementary blocks and an inlet andoutlet duct. A channel parallel to the axis passes through theelementary blocks and the screens and serves as a collector for theflows coming from the screens or going to them.

According to this document, the elementary blocks are made of sinteredmetal and are therefore dimensionally stable, particularly with respectto the above-mentioned stresses of temperature and pressure. The purposeof the walls is simply to position the blocks.

Such an absorbent material has many disadvantages: the quantity of gaswhich it is capable of absorbing per unit volume is relatively limitedand it retains the absorbent particles badly. It is this which makes itnecessary to pass the gaseous flow through screens which serve as a kindof filter but which slow down the flow and which also, in the long term,risk becoming loaded with particles trying to escape the elementaryblocks. Furthermore, the necessity of providing such screens furtherincreases the already large volume which is necessary due to therelatively poor absorption performance of the blocks themselves.Finally, as these blocks are made of metal, preferably of stainlesssteel, the weight of the assembly is high.

From U.S. Pat. No. 2,384,460 there is also known a reactor in which thereagent is a powder liable to swell when it absorbs the refrigeratinggas. This powder is housed in a cylindrical body and is confined in aspecified volume. For the transfers of mass between the absorbentmaterial and the gas duct, the space reserved for the material istraversed by perforated tubes filled with glass wool in order to preventthe particles from escaping with the gaseous flow. The featureconsisting of a filter supposed to retain the particles and to allow thegaseous flow to pass is therefore found again in a slightly differentway. It will however be understood that the designer of this knowndevice accepts that the particles will pass through the perforations ofthe tube. Otherwise, he would not have provided the glass wool in thetube. Consequently, there will be an increasing number of particles inthe glass wool, and then, finally, in the gaseous flow itself, that isto say precisely what had not been wanted.

From EP-A-0206875 there is also known a solid reagent formed from amixture of chloride and an expanded derivative of carbon having alaminar structure. This reagent solves the mass and heat transferproblems. It is capable of absorbing large quantities of gas per unitvolume.

On the other hand, its mechanical strength is low and it has a tendencyto deform rapidly under the effect of the pressure gradients and volumevariations encountered during the functioning of the machine. Inparticular, when the reagent absorbs gas by chemical combination, itsvolume tends to increase progressively. Following this, the chemicalseparation can be incomplete and the surfaces of the reagent providedfor the mass exchanges can be so deformed that they become inefficient.For example, if cavities have been provided in the block of reagent inorder to increase the exchange area, these cavities tend to close in onthemselves after several refrigeration-regeneration cycles.

The purpose of the invention is therefore to propose a chemical reactorfor a refrigerating machine or similar which is capable of ensuring goodrefrigeration performance and retaining such performance over manysuccessive cycles without prohibitive deterioration of its initialcharacteristics.

According to the invention, the chemical reactor for a refrigeratingmachine or similar comprising a block of reagent intended to absorb bychemical combination a gaseous flow coming from an evaporator and todesorb this flow by reverse chemical reaction under the effect of a risein temperature, the block of reagent being confined between confiningfaces at least some of which are permeable to mass exchanges, ischaracterised in that the block is capable of volume variation as afunction of the quantity of gas absorbed and in that the confining facesare part of confining walls capable of providing the block with shapestability in opposition to the tendency to the said volume variations.

It was in fact noticed that the reagent, despite its tendency toincrease in volume during the chemical reaction of combination with therefrigerating fluid, withstood being confined in a substantially fixedvolume without disadvantage. In particular it was found that this had anegligible influence on its capacity to absorb chemically a largequantity of refrigerating gas. On the contrary, the confinementstabilises the physical structure of the block, which effect isfavourable for obtaining good absorption and desorption performance.

Thus, according to the invention, the block of reagent is confined in asubstantially fixed volume and, as this block is solid, it has a goodintrinsic cohesion in service due to which the active substance is wellretained in its interior. The problems of escaping of reagent found arethus overcome with simple permeable walls, which can for example beperforated walls.

It is no longer necessary to cause the gaseous flow to pass through moreor less efficient filters in order to retain particles.

Due to the invention, a reliable reactor is produced for the first timewhich is capable of storing quantities of gas in a restricted volume andmaking it possible to envisage the efficient production of cold using anabsorption device. For example, unlike the absorption refrigeratorsknown at present and which in fact are only coolers, a device accordingto the invention is capable of producing ice whilst being placed in ahigh external temperature (of tropical type) without its size or itsweight exceeding usual standards.

The reactor according to the invention can receive most if not allreagents containing chlorides.

The permeable walls can for example be constituted by perforated tubes,lining parallel channels formed in the block.

During the combination reaction, it is important to extract the heatproduced in order to prevent the reagent from heating up andconsequently becoming less eager for the gas.

For this purpose, it is possible to secure on a peripheral wall, beingone of the confining walls, cooling fins exposed to a natural or forcedflow of cooling air.

On the contrary, during regeneration, it is advantageous that the heatdissipation should be as low as possible. That is why the fins areplaced in an annular chamber defined externally by a heat-insulatingouter casing. During refrigeration, this outer casing channels thecooling air along the fins. During regeneration, the space surrounded bythe outer casing is at least partially isolated from the exterior inorder to prevent convection flow along the fins.

In order to heat up the reagent during regeneration, there is preferablyused an electrical resistance heating element, fitted in a housinglocated in the centre of the block in order that the heat produced bythis element diffuses through the block with practically no losses.

If desired, it is possible to line this housing with a confining wall,but it is also acceptable not to line the housing, accepting that thesubstance of the block, because of its tendency to swell, should clampthe heating element. Conduction between the heating element and theblock will only be better for this. It will of course be necessary toensure the use of heating element whose surface temperature does notexceed the acceptable limit temperature for the substance of the block.

With the heating element in the center of the block and the fins at itsperiphery, the harmful tendency of the fins to act as a thermal diffuserduring the regeneration is efficiently countered.

According to its second aspect, the invention also relates to arefrigerating machine comprising, in closed circuit, a high pressurereservoir, a pressure reduction device, an evaporator and a reactoraccording to the first aspect.

According to its third aspect, the invention furthermore relates to acontainer provided with a refrigerating machine according to the firstaspect.

According to a fourth aspect, the reagent cartridge, in particular inorder to become part of a reactor according to the first aspect, of arefrigerating machine according to the second aspect or of a containeraccording to the third aspect, comprises a block of reagent enclosed ina fluid-tight casing, this block comprising cavities opening through thefluid-tight casing and closed in a fluid-tight manner by temporaryobturations.

Such a cartridge allows the handling and storage of the reagent withoutdeterioration of its properties in particular without absorption ofdampness, from its manufacture until its use in the reactor.

Other features and advantages of the invention will further emerge fromthe following description relating to non-limitative examples.

In the accompanying drawings:

FIG. 1 is a schematic diagram of a refrigerating container according tothe invention, during refrigeration;

FIG. 2 is a view similar to FIG. 1 but during regeneration;

FIG. 3 is an axial cross-section view of the reactor of FIGS. 1 and 2;

FIG. 4 is a transverse cross-section view of the reactor of FIGS. 1 and2; and

FIG. 5 is a partial view of a variant embodiment.

In the example shown in FIG. 1, the refrigerating machine 1 provided forthe refrigerating container 2 comprises a reserve or tank of liquidrefrigerating fluid 3 subject to its own saturated vapour pressure. Thefluid is, in particular, chosen such that this pressure is relativelyhigh. In this example, this fluid is ammonia whose saturated vapourpressure is of the order of 1.5 MPa at 20° C. An outlet orifice 4,provided at the bottom of the tank 3 in order to allow only liquid toemerge, is connected to a pressure reduction device 6 by theintermediary of a stop valve which can be an electro-valve powered by arechargeable battery attached to the container. The pressure reductiondevice 6 is located at the input of an evaporator 8 whose output isconnected by a T connector 10 on the one hand to a reactor 9 and on theother hand to a condenser 11. The condenser 11 is itself connected to aninput 12 located at the top of the tank 3.

The pressure reduction device 6 and the evaporator 8 are located insidethe heat-insulated enclosure 5 of the refrigerating container 2 whilstthe other elements described up to this point are located outside of theenclosure 5. A non-return valve 13 prevents the fluid coming from thereactor 9 from flowing in the direction of the evaporator 8, whilstanother non-return valve 14 prevents the fluid contained in the tank 3from flowing towards the condenser 11.

An overheating measurement device 16, of known type, controls the degreeof opening of the pressure reduction device 6 such that the fluidemerging from the evaporator 8 is completely evaporated without beingexcessively overheated.

In a way which will be described in greater detail below, the reactor 9contains a reagent, preferably that known from EP-A-0477343/WO-A-9115292constituted by a mixture of chloride and an expanded carbon derivativewith laminar structure, having the property of combining chemically withthe refrigerating fluid used, ammonia in this instance, when itstemperature is low, and of being chemically separated from the ammoniawhen its temperature assumes a predetermined high value.

That is why the reactor 9 comprises means for selectively allowing it tobe heated or cooled. The means of heating it essentially comprise aheating element 17 which is selectively actuated by a switch 18. In amanner which is not shown, the heating element can be thermostatcontrolled. The means of cooling the reactor 9 comprise a fan 19 poweredby the rechargeable battery attached to the container. The fan 19 causesa convection air flow to circulate inside an outer casing 21 of thereactor. The casing 21 is heat-insulating in order to limit heat lossesduring the heating and comprises, at its base, a flap 22 which is closedduring the heating in order to prevent the chimney effect. On thecontrary, the flap 22 is open while the fan 19 is operating.

The general functioning of the refrigerating machine shown in FIGS. 1and 2 will now be described.

When the machine is waiting to operate as a refrigerator, the stop valve7 is closed such that the reserve of refrigerating fluid is trappedbetween the non-return valve 14 and the valve 7. Its pressure is highsince it corresponds to the saturated vapour pressure of ammonia at theexternal temperature, for example 20° C.

In order to initiate a refrigeration cycle, it suffices to open the stopvalve 7 and the flap 22, and to cause the fan 19 to operate. The liquidleaves the tank 3 through the outlet 4 and the valve 7, and then passesthrough the pressure reduction device 6 whilst losing pressure, whichallows it to vaporise in the evaporator 8 whilst extracting thenecessary latent heat of vaporization from the cold chamber of thecontainer. The gas thus formed passes through the non-return valve 13 inthe forward flow direction and then reaches the reactor 9 where,considering the low temperature maintained by the fan 19, the gaschemically combines with the reagent. The refrigerating effectdisappears when the reagent is substantially saturated by the ammonia,the tank 3 being then at its low level.

It is then necessary to proceed to a regeneration cycle, as shown inFIG. 2. For this purpose, the valve 7 and the flap 22 are closed,operation of the fan 19 is interrupted and the heating element 17 isbrought into operation using the switch 18. Provision can also be madeto close the upper end of the casing 21 by means, for example, of anobturator 23.

The heating of he reagent by the element causes separation of theammonia which leaves in the gaseous state through the same pipe 24 asthat through which it was brought into the reactor. Considering therelatively high temperature in reactor, the pressure of the gas leavingit tends to be higher than the equilibrium temperature in the tank 3such that the gas passes through the non-return valve 14. It is thenreturned to the ambient temperature, such as 20° C., in the condenser 11in order to return to the liquid state in the tank 3. When the reagentis rid of almost all of the mobile ammonia (after putting into service,a certain quantity of ammonia remains permanently trapped in the block),the regeneration cycle stops. A new refrigeration cycle can begin. Thetank 3 is then at its high level.

Such a container has the advantage of being able to undergo theregeneration process when it is in store, and may then be autonomous inenergy in order to ensure the refrigeration of foodstuffs contained inthe container during the transport of the container.

The reactor 9 will now be described in detail with reference to FIGS. 3and 4.

The block of reagent 26 has a generally cylindrical shape having thesame axis 27 as the casing 21 and a diameter less than the internaldiameter of the casing 21.

In the example shown, the block 26 consists of a stack of elementarydisk-shaped blocks 28.

According to the invention, the block 26 is enclosed in confining wallswhich are preferably made of stainless steel in order to be mechanicallystrong and to resist corrosion.

The confining walls comprise, in particular, a cylindrical casing 29into which the elementary blocks 28 are fitted such that they arelightly clamped initially. This clamping is intended to increase afterthe reactor is used because of the tendency of the reagent to swell asexplained above. The casing 29 therefore has a function of hooping theblock 26.

The peripheral casing 29 is closed at each axial end of the block 26 bya closure plate 31 of circular shape. The block 26 is traversed by acertain number (four in the example) of channels 32 of cylindricalshape, which are parallel with the axis 27 and distributed angularlyaround the latter. The channels 32 coincide with openings 33 formedthrough the plates 31 and thus emerge on the outside of the confiningcasing of the block 26. The channels 32 are surrounded by permeableconfining walls consisting of perforated tubes made of stainless steel34. The perforations of the tubes 34 allow mass exchanges between thegaseous medium of the channels 32 and the block 26 which is exposed tothis medium though the perforations. The annular ends of the perforatedtubes 34 are contiguous with the corresponding peripheries of theopenings 33.

In each of the two annular regions where the outer casing 29 isconnected to one of the confining plates 31, the outer casing 29 is alsoconnected in a fluid-tight manner to an upper closure cap 36 and to alower closure cap 37 respectively. An upper cross-piece 38 and a lowercross-piece 39 respectively are fitted in a substantially centralposition between each cap, 36 or 37 respectively, and the adjacentconfining plate 31.

A distribution and collecting chamber 41 is defined between the uppercap 36 and the adjacent confining plate 31 and consequently is connectedto the channels 32 through the openings 33. The upper cross-piece 38comprises ducts 42 which connect the collection and distribution chamber41 with the inlet and outlet duct 24 in the reactor 9, through a bore 43in the upper cap 36 and an inlet and outlet orifice 44 in the reactor.The lower cap 37 and the corresponding confining plate 31 togetherdefine a circulation chamber 50.

The heating element 17 is an electrical element in the form of a rodwhose useful length corresponds to the axial length of the block 26 andwhich is fitted substantially with no play in an axial housing 46provided through the whole axial length of the block 26. The upper endof the housing 46 is closed by the plate 31 adjacent to the chamber 41.According to a first embodiment shown in the left hand section of FIG.3, the housing 46 is not lined so that, in operation, the reagent,taking account of its tendency to swell, clamps the heating element 17with the advantage of improving the thermal contact between them.

On the other hand, as shown in the right hand section of FIG. 3, if itis feared that the temperature of the heating element 17 may damage thesurrounding reagent, it is also possible to line the housing 46 with atube 47. If the latter is impermeable, in particular not perforated, itprotects the heating element 17 from corrosion.

The heating element is fitted through a bore 48 in the lower cap 37 anda central bore 49 in the lower cross-piece 39. The latter thereforeserves as a mounting for the heating element 17. It can for example bethreaded internally in order to receive a corresponding thread of theelement 17 for the purpose of fixing it. The lower confining plate 31has a central opening 51 to allow the element 17 to pass through.

In order to prevent leakages of ammonia to the exterior, the peripheralcasing 29 is fluid-tight and it is connected in a fluid-tight manner tothe upper 36 and lower 37 caps. The latter are also fluid-tight, withthe exception of their respective bores 43 and 48, which are connectedin a fluid-tight manner with the internal passages 42 and 49 of theirrespective cross-pieces 38 and 39, as well as, in the case of the uppercap 36, with the orifice 44 provided for connection with the rest of therefrigeration circuit. The heating element 17 is fitted in a fluid-tightmanner in the bore 49.

The peripheral wall 29 and the outer casing 21 between them define anannular chamber 52 intended for the rising circulation of the coolingair flow produced by the fan 19 (not shown in FIG. 3) which is below thelower cap 37. The assembly constituted by the reagent block 26, theconfining walls 29, 31, 32 and the caps 36 and 37 together with theheating element 17 is supported inside the outer casing 21 by anyappropriate means such as brackets 53 allowing the passage of the airflow 54.

The peripheral wall 29 carries fins 56 protruding into the annularchamber 52 towards the outer casing 21. The fins 56 are disposed inaxial planes in such a way as to define between them air circulationchannels 57 (FIG. 4) parallel with the axis 27. The fins 56 are, forexample, made from sections of T-shaped aluminium profile welded to theexternal surface of the peripheral casing 29.

At its upper end, the outer casing 21 is closed by a wall 58 withopenings, whose openings 59 can be closed selectively by an obturatingdisk forming the obturator 23 shown schematically in FIG. 2.

The functioning of the reactor 9 is as follows:

while it is functioning in refrigeration, the gaseous ammonia, cold andpressure-reduced, reaches through the orifice 24 the distribution andcollection chamber 41 and then the channels 32 before being absorbed bychemical combination with the reagent 26 through the perforations in theconfining tubes 34. The flap 22 is open, as shown in FIG. 1, and theobturator 23 is also in the open position, as shown in FIG. 3. The fan19 operates and generates the cooling air flow 54 which removes the heatof the exothermic combination reaction. The flow 54 is accelerated bythe chimney effect inside the outer casing 21, because of thetemperature of the fins 56 which are heated up by the reaction heat.

During regeneration, the operation of the fan 19 is interrupted, theflap 22 and the obturator 23 are closed and the heating element 17 isput into operation in order to bring the reagent up to a temperaturewhich can be of the order of 200° C. This results in an endothermicchemical separating reaction between the reagent and the ammonia, whichis released in the gaseous state through the perforations of the tubes34 and then through the inlet and outlet orifice 44, via thedistribution and collection chamber 41 and the ducts 42 of thecross-piece 38.

As the annular chamber 52 is isolated from the exterior at this stage,the fins 56 no longer take any part in heat evacuation, so that theendothermic reaction takes place with a good yield.

The confining plates 31, even though flat, effectively resist thetendency of the block to swell as they are adjacent to the chambers 41and 50 in which the pressure of the gaseous ammonia exists.

The strength of the plates 31 is increased by the connection betweenthem provided by the perforated tubes 34 and (if provided) thenon-perforated tube 47, and also by the cross-pieces 38 and 39 whichtransfer the swelling thrust to the caps 36 and 37 which are strongbecause of their domed shape. This reinforcement provided to the plates31 is useful when the pressure in the chambers 41 and 50 is low whilstthe swelling tendency of the block is at a maximum, for example at theend of a refrigeration cycle.

In the embodiment shown in FIG. 5, the elementary blocks 28 areprefabricated cartridges having their own outer casing 60 which isfluid-tight apart from the openings 61 for the passage of the perforatedtubes 34 and the heating element 17.

The casing 60 has a simple sealing and mechanical cohesion function butit is not designed to withstand the operational pressure.

When manufacturing the cartridges, the openings 61 are obturated withfrangible fluid-tight obturators 62 made, for example, from fluid-tightpaper. During assembly, the peripheral wall 29, the lower cap, the lowerconfining plate 31, the lower cross-piece 39, the perforated tubes 34and the heating element 17 are assembled first, then the elementaryblocks 28 are stacked inside the peripheral wall 29 whilst the heatingelement 17 and the tubes 34 each perforate two obturators 62 of eachblock when they enter into and emerge from the bore 63 or 64respectively. The bores 63 and 64 are not lined. The function of theobturators 62 is to protect the block from unwanted absorption ofdampness before it is assembled.

The assembly of the core of the reactor is completed by the putting intoposition of the plate 31 and of the upper cap 36.

The embodiment shown in FIG. 5 simplifies the assembly of the reactor bytransferring a certain number of precautions, in particular hygrometricones, to the manufacture of the blocks alone.

The invention is of course not limited to the examples described andshown.

The plates 31 could also be perforated in order to increase the massexchange areas.

It would be possible to close only the top or the bottom of the outercasing in order to interrupt the cooling air flow during regeneration.

It would be possible for there to be several cross-pieces in eachchamber and several heating elements in the block.

The reactor could have two different points of access, one for the inputof ammonia during refrigeration and the other for the output of ammoniaduring regeneration.

I claim:
 1. A chemical reactor for a refrigerating machine including asupply of reagent intended to absorb by chemical combination a gaseousflow coming from an evaporator and to desorb this flow by reversechemical reaction under the effect of a rise in temperature, the reagentbeing confined between confining faces at least some of which arepermeable to mass exchanges, characterized in that the reagent is formedas at least one solid block of reagent prior to its installation in thereactor between said confining faces so that said block is capable ofvolume variations as a function of the quantity of gas which it hasabsorbed, and in that the confining faces are part of confining wallsconfigured to exert an initial light clamping force upon said at leastone block which is capable of providing the block with shape stabilityfor resisting said volume variations.
 2. A reactor according to claim 1,characterized in that the permeable confining walls are perforated wallsinterposed between the substance of the block and a space forcirculation of the gaseous flow.
 3. A reactor according to claim 1,characterized in that the permeable walls are tubes which line recessesformed in the block.
 4. A reactor according to claim 3, characterized inthat the recesses are channels parallel with one another.
 5. A reactoraccording to claim 3, characterized in that, at at least one of theirends, the recesses open in a chamber adjacent to one of two oppositefaces of the block of reagent.
 6. A reactor according to claim 5,characterized in that the chamber is separated from the block by aconfining plate which is one of the confining walls of the block andthrough which the recesses open.
 7. A reactor according to claim 6,characterized in that the chamber adjacent to one of the ends of theblock is connected with an orifice for connection with a refrigerationcircuit.
 8. A reactor according to claim 6, characterized in that atleast one cross-piece extends between the confining plate and anopposite wall also delimiting the chamber.
 9. A reactor according toclaim 8, characterized in that in the cross-piece there is formed apassage connecting the chamber with a refrigeration circuit.
 10. Areactor according to claim 8, characterized in that the cross-piece ishollow and allows the passage and fixing of a heating element engaged ina cavity formed in the block of reagent and opening through theconfining plate opposite the cross-piece.
 11. A reactor according toclaim 4, characterized in that the channels are distributed around acavity formed in a substantially central position in the block andaccommodate a heating element.
 12. A reactor according to claim 1,characterized in that the block comprises a cavity in which a heatingelement is mounted.
 13. A reactor according to claim 10, characterizedin that the heating element is fitted substantially without play in thecavity, which is delimited by surfaces which are part of the block ofreagent.
 14. A reactor according to claim 10, characterized in that thehousing is delimited by one of the confining walls.
 15. A reactoraccording to claim 6, characterized in that the confining plate isconnected by its periphery to a peripheral hooping casing of the block,being one of the said confining walls.
 16. A reactor according to claim15, characterized in that, in the region in which the confining plate isconnected to the peripheral casing, the confining walls are connected tothe peripheral edge of an end cap.
 17. A reactor according to claim 1,characterized in that the block is of cylindrical shape and theconfining walls comprise a peripheral hooping casing.
 18. A reactoraccording to claim 1, characterized in that the confining walls comprisea peripheral casing carrying cooling fins protruding into an annularchamber contained between the peripheral casing and an outer casing. 19.A reactor according to claim 18, characterized in that the fins areoriented in such a way as to define between them parallel aircirculation channels, preferably vertical.
 20. A reactor according toclaim 18, characterized by means for selectively providing andpreventing the circulation of air in the annular chamber.
 21. A reactoraccording to claim 18, characterized in that the outer casing isheat-insulated.
 22. A reactor according to claim 18, characterized inthat the confining walls are made of stainless steel and the fins aremade of aluminum.
 23. A reactor according to claim 18, characterized inthat the fins are formed from sections of profiled material fixed to theperipheral casing.
 24. A reactor according to claim 15, characterized inthat the block is fired such that it is lightly clamped in theperipheral casing.
 25. A reactor according to claim 1, characterized inthat the block comprises a plurality of disk-shaped elementary blocksslipped in stacked fashion one after the other into a space defined bysaid confining walls.
 26. A refrigerating machine, including in a closedcircuit, a high pressure reservoir, a pressure reduction device and achemical reactor for a refrigerating machine having a supply of reagentintended to absorb by chemical combination a gaseous flow coming from anevaporator and to desorb this flow by reverse chemical reaction underthe effect of a rise in temperature, the reagent being confined betweenconfining faces at least some of which are permeable to mass exchanges,characterized in that the reagent is formed as at least one solid blockof reagent prior to its installation in the reactor between saidconfining faces so that said block is capable of volume variations as afunction of the quantity of gas which it has absorbed, and in that theconfining faces are part of confining walls configured to exert aninitial light clamping force upon said at least one block which iscapable of providing the block with shape stability for resisting saidvolume variations.
 27. A container provided with a refrigerating machineincluding in a closed circuit, a high pressure reservoir, a pressurereduction device and a chemical reactor for a refrigerating machinehaving a supply of reagent intended to absorb by chemical combination agaseous flow coming from an evaporator and to desorb this flow byreverse chemical reaction under the effect of a rise in temperature, thereagent being confined between confining faces at least some of whichare permeable to mass exchanges, characterized in that the reagent isformed as at least one solid block of reagent prior to its installationin the reactor between said confining faces so that said block iscapable of volume variations as a function of the quantity of gas whichit has absorbed, and in that the confining faces are part of confiningwalls configured to exert an initial light clamping force upon said atleast one block which is capable of providing the block with shapestability for resisting said volume variations.
 28. A reagent cartridge,in particular for being part of a reactor for a refrigerating machineincluding a supply of reagent intended to absorb by chemical combinationa gaseous flow coming from an evaporator and to desorb this flow byreverse chemical reaction under the effect of a rise in temperaturecomprising,said reagent being formed as at least one solid block priorto its installation in the reactor, said at least one block beingconfigured for confinement between confining faces at least some ofwhich are permeable to mass exchanges, said at least one block beingcapable of volume variations as a function of the quantity of gas whichit has absorbed and in that the confining faces are part of confiningwalls configured to exert an initial light clamping force upon said atleast one block which is capable of providing the block with shapestability which resists said volume variations; and said at least oneblock of reagent being enclosed in a fluid-tight casing, said blockhaving cavities emerging through the fluid-tight casing and closed in afluid-tight manner by temporary obturations.